Category Archives: Dennis Ritchie

A great has passed on – Dennis Ritchie

We pay tribute to another great and perhaps even greater than Steve Jobs in his contribution to the computer industry. Dennis Ritchie, the creator of the C Programming Language and co-developer of the Unix Operating Systems, has passed away at 70.

If you think about how his work has influenced and spawn the birth of other programming languages such as C++, Java, and other C variants as well as the ideas and the foundation of Linux, Solaris, HP-UX, FreeBSD and so on, that’s massive.

It was him that made me a Unix bigot, a true believer that technology should be shared because sharing means giving life to ideas and innovations.

In my books collection, these are 2 of my most coveted books and Dennis Ritchie was very much part of the contents and ideas in the books.

C and Unix Programming Books

I would like to share a few excerpts from the book, ” A Quarter Century of Unix” by Peter H. Salus (ISBN #: 0-201-54777-5). In page 48,

Mike Mahoney asked Dennis Ritchie about designing C:

“It was an adaptation of B that was pretty much Ken’s. B actually started out as system FORTRAN… Anyway, it took him about a day to realize that he didn’t want to do a FORTRAN compiler after all. So he did this very simple language called B and got it going on the PDP-7.  …”

“The basic construction of the compiler – of the code generator of the compiler – was based on an idea I’d heard about; some at the [Bell] Labs at Indian Hill. I never actually did find or read the thesis, but I had the ideas in it explained to me, and some of the code generator for NB, which became C, was based on this Ph.D thesis. It was also the technique used in the language called EPL, which was used for switching systems  and ESS machines;it stood for ESS Programming Language. So that the first phase of C was really these two phases in short succession of, first, some language changes from B, really, adding the type syntax structure without too much change in the syntax and doing the compiler”

“The combination of things caused Ken to give up that summer. Over the year, I added structures and probably made the compiler somewhat better – better code – and so over the next summer, we made the concerted effort and actually did redo the whole operating system in C”

This was from 1971-1973, at Bell Telephone Labs (BTL), where some of the most important chain of event happened. In the summer of 1972, the hardware arrived:

DEC PDP-11/20 processor
56 Kbytes of core memory
High-speed paper tape reader/puch
ASR-33 Teletype - console
DECtape - twin drive
RK11/RK05 disk (2) - 2.4 Mbytes
RF11 fixed head disk (2 at first, 3 more added later)
DC11 (6 lines) for local terminals
DM11 16-line multiplexers (3)

This was the machine that wrote the history on Unix. This was the machine that ran the Unix that was completely rewritten in C. Ken Thompson, Dennis Ritchie, Joe Ossanna, were all part of Unix history.

Earlier in 1970, Dennis Ritchie recounts the history of Unix:

“Unix came up in two stages. Ken got it going before there was a disk, he divided the memory up into two chunks and got the operating system going in one piece and use the other piece for a sort of RAM disc. To try it out, you’d first load this paper tape that initialized the disk and then load the operating system. So there was a cp [copy file], a cat [catenate files] , and an ls [list files] actually running before there was a disc”. 

Classic stuff!

My last bow of respect to Dr. Dennis Ritchie, the creator of the C Programming Language and co-developer of the Unix Operating System (with Dr. Ken Thompson).